Lk = S/2 + K2
The e-chain glides on one half of the lower run and on the other half on a glide bar, as shown in the picture above.
Lk = length of the e-chain
S = length of travel
S/2 = half length of travel
R = bend radius
ΔM = deviation from the centre point
K2 = add-on (with lowered moving end)